Supporting device for return headers



Dec. 17, 1946. J. E. DONAHUE ET AL SUPPORTING DEVICE FOR RETURN HEADERSFiled Feb. 5, 1945 Patented Dec. 17, 1946 John E. Donahue and Leo W.Schrader, Elizabeth, N. J., assignors to Standard Oil DevelopmentCompany, a corporation of Delaware Application February 5, 1943, SerialNo. 474,790

3 Claims.

The present invention relates to improvements in furnace construction,and more particularly, to an improved means for supporting andprotecting the tube return headers in a furnace.

For illustration, one concrete embodiment of this invention is shown inthe sectional perspective view of the accompanying drawing.

It has heretofore been the common practice in constructing tube chambersin furnaces, particularly in the radiant section, to support the sets orbanks of tubes and the individual tubes of the sets or banks by tubesheets and intermediate hangers exposed to the effect of heat and gasesfrom the combustion chamber. These tube sheets and hangers must beconstructed from special alloys in order to enable them to resist thecorroding effect of the gases and the intense heat in the combustionsection of the furnace. The use of these heat resistant alloys increasesthe cost of the heater materially, particularly when it is realized thatin a typical installation, usin long horizontal tubes, as many as threeintermediate alloy tube supports per pair of tubes are required. inaddition to those used at the tube ends to support the header boxes.

By eliminating the use of end alloy tube sheets protecting the headerboxes and header-box supports and supporting the tubes, a large part ofthis cost could be avoided.

Consequently, one of the primary objects of the present invention is theprovision of a constructional arrangement in the radiant section of thefurnace whereby the tubes are supported at their ends in such a way thatthe relatively expensive alloy tube sheets are replaced by lessexpensive refractory and the return headers are shielded from the directheat of the furnace and are protected from the action of the flue gases.

Another important object of the present invention is to provide anarrangement whereby the tube headers are independently supported behinda wall which protects them from the combustion gases, the supports beingso arranged that the tube headers, supports, chamber walls, etc., maymove relative to one another under the influence of expansion andcontraction forces without strains or stresses leading to deteriorationand after reading the following description and claims and afterconsidering the accompanying drawing which is a perspective view of thepreferred form of this invention with parts cut away.

The portion of the furnace structure chosen for illustration comprisesside Wall I, end walls 2 and 3, and roof 4 forming the usual combustionsection of a furnace. Disposed across the combustion space are rooftubes 5 which terminate in the customary type of return headers 6. Thesereturn headers are enclosed in a housing 1 provided with hinged doors 8which permit ready access to the fittings, header boxes, and the like.

This housing may be attached to the furnace in any suitable manner; forexample, it may be attached to the furnace wall by means of supportingI-beams 9 and brackets In. That portion of the housing nearest thefurnace interior is constructed of a suitable refractory materialforming wall I l which serves to screen the housing, the headers, andother fittings contained therein from the effects of the radiant heat ofthe furnace and from the combustion gases. This wall ispreferablysupported on top of the usual furnace wall 3 and is connectedto the roof 4 thru I-beam l2, although it may be simply a continuationof wall 3. The wall II may also be additionally supported by means ofsteel plate I 3.

Where tubes 5 pierce thru wall t2, the opening between the tubes and therefractory brick may be sealed in any desirable manner as by asbestosrope packing l4.

The tube headers may be supported in the housing by resting them onrollers l5 which are in turn supported by angle-iron supports I6restingon I-beam IT, or they may be supported in any other desirablemanner, such as by U-bolts or J-bolts, so that the headers are free toexpand or contract with the tubes in accordance with the change intemperature and conditions in the combustion zone of the furnace.

The present invention, therefore, eliminates the usual alloy tube sheetfor supporting the ends of furnace tubes, particularly in the radiantsection of the furnace, and provides, instead, means for supporting thetube headers independently behind a tile wall which acts to protect theheaders and fittings from the intense heat of the combustion zone andfrom the oxidizing effect of the combustion gases. Furthermore, theheaders and their supports and tubes are free to expand or contract inaccordance with the temperature changes in the furnace.

The nature and objects of the present in vention having thus been setforth and a specific illustrative embodiment of the same given, what isclaimed and desired to be secured by Letters Patent is:

1. In a furnace, the combination comprising bottom, top and side wallsforming a combustion zone in said furnace, tubes disposed across saidcombustion zone and extending through said side walls, in sealedrelation thereto, and provided for longitudinal movement through saidwalls, header members connecting the ends of each tube with an adjoiningtube exteriorly of the combustion zone, and means, independent of saidside walls, supporting each of said header members for sliding movementwith its connected tubes, with respect to the supporting means and toany other header member.

2. A furnace according to claim 1 wherein said supporting means compriserollers arranged 4 substantially horizontally, forming a substantiallyright angle with said tubes.

3. In a furnace the combination comprising bottom, top and side wallsforming a combustion zone in said furnace, tubes horizontally disposedacross said combustion zone and extending with free play through saidside walls, return headers for each end of said tubes horizontallydisposed outside said walls and connecting pairs of tubes arranged inthe same horizontal plane and individual roller means exterior andindependent of said walls for loosely supporting said headersindividually and arranged beneath and substantially parallel to saidheaders, said headers being free to move independently from the motionsof any other header and without affecting the means supporting any otherheader.

' JOHN E. DONAH'UE. LEO W. SCHRADER.

